Area Forecast Discussion
Issued by NWS Aberdeen, SD

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716
FXUS63 KABR 162333 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
633 PM CDT SAT MAY 16 2015

.UPDATE...
ISSUED AT 627 PM CDT SAT MAY 16 2015

TOR WATCH REMAINS IN EFFECT ACROSS THE FAR EASTERN CWA THIS
EVENING. MOST ACTIVITY LOOKS LIKE IT WILL REMAIN FARTHER EAST
UNTIL THE NEXT ROUND OF SHORTWAVE ENERGY PUSHES NORTH SUNDAY
MORNING. ADJUSTED POPS THIS EVENING AND OVERNIGHT BASED ON LATEST
RADAR TRENDS AND HI-RES MODEL PRECIP AND SHORTWAVE TIMING.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 301 PM CDT SAT MAY 16 2015

STORMS HAVE BEGUN TO PULSE ALONG THE WARM FRONT WITH AN AIRMASS THAT
CONTINUES TO WARM THROUGH FILTERED CLOUD COVER. SEVERE POTENTIAL
REMAINS THANKS TO FAVORABLE SHEAR ENVIRONMENT...AND INCREASING CAPE
MAINLY ALONG AND NORTHEAST OF A LINE FROM KPHP KPIR TO KHON.

THE ASSOCIATED WEAK WAVE CONTINUES TO DRIFT NORTH THIS
AFTERNOON/EVENING...WITH A LESS FAVORABLE UPPER LEVEL ENVIRONMENT
FOR A FEW HOURS BEFORE THE NEXT WAVE IN CENTRAL NEBRASKA LIFTS NORTH
AND WEAKENS. THE MAIN UPPER FEATURE PIVOTS UP INTO THE CWA SUNDAY
AM...WITH A Q VECTOR BULLSEYE OVER THE CWA. SREF PROBABILITIES FOR
EXCEEDING 1 TO 2 INCHES OF RAIN ARE NEAR 80 AND 30 PERCENT
RESPECTIVELY...WITH MOST GUIDANCE SET ON THE JAMES VALLEY RECEIVING
THE HEAVIEST RAINFALL. AS THE UPPER TROF CONTINUES NORTHEAST...WE
WILL SEE FAR EASTERN COUNTIES GET INTO THE WARM SECTOR...A HIGH
SHEAR LOW CIN ENVIRONMENT WHERE ANY DAYTIME HEATING WILL LEAD TO
RAPID DESTABILIZATION...ALBEIT WELL AHEAD OF THE COLD FRONT.
THUS...BROUGHT IN A LATE MORNING MENTION OF SEVERE FOR EASTERN
SD/WESTERN MN SUNDAY.

AS THE UPPER LOW MOVES EAST...WILL SEE STRONG COLD ADVECTION WITH
850MB WINDS APPROACHING 50KTS. MIXED DOWN WINDS ARE WELL WITHIN
ADVISORY CRITERIA. GFS 850MB TEMPS FALL TO -4C...WITH THE ECMWF
STILL AROUND -7C. NAM LOW LEVEL ENVIRONMENT SUGGESTS THE POTENTIAL
FOR GRAUPLE SHOWERS WITH DAYTIME HEATING MONDAY UNDER THIS VERY COLD
ENVIRONMENT. THE GRADIENT MAY REMAIN STRONG ENOUGH FOR LIGHT WINDS
TO PERSIST THROUGH PARTS OF TUESDAY MORNING IN THE EAST...WHERE
850MB WINDS ARE COLDEST...WHILE IN THE WEST THE HIGH CENTER MOVES
OVERHEAD FOR FAVORABLE RADIATIONAL CONDITIONS. WHILE FREEZE
POTENTIAL IS MARGINAL FOR MONDAY MORNING...IT LOOKS ALMOST CERTAIN
FOR TUESDAY MORNING.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 301 PM CDT SAT MAY 16 2015

NOT MUCH HAS CHANGED IN THE EXTENDED FORECAST COMPARED TO 24 HOURS
AGO. STILL LOOKS A BIT COOLER THAN CLIMO NORMAL AS THE PERIOD OPENS
WITH COOL DRY CANADIAN HIGH PRESSURE OVER THE REGION. STILL SOME
QUESTION AS TO HOW COLD IT CAN GET BY TUESDAY MORNING...BUT FOR NOW
WILL CONTINUE TO MONITOR TEMPERATURE FORECAST TRENDS IN CASE THERE
IS A NEED FOR A FROST OR FREEZE HEADLINE HEADING INTO TUESDAY
MORNING. OTHERWISE...IT STILL LOOKS LIKE THE FLOW PATTERN WILL
RECYCLE BY MID TO LATE WEEK WITH ONE AREA OF LOW PRESSURE SKIRTING
THE CWA ANCHORED MAINLY ON WEDNESDAY AND STILL MAINLY ACROSS THE
SWRN FORECAST ZONES...AND THEN ANOTHER SHIFT IN THE FLOW ALOFT TO
SOUTH-SOUTHWESTERLY BY NEXT WEEKEND WITH ADDITIONAL SHOWER AND
THUNDERSTORM CHANCES RAMPING UP AS TEMPERATURES RECOVER TO CLOSER TO
NORMAL IN LOW LEVEL SOUTHERLY RETURN FLOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 627 PM CDT SAT MAY 16 2015

SHOWERS AND TSTORMS WILL CONTINUE TO IMPACT THE REGION THIS
EVENING. KATY HAS THE BEST CHANCE OF SEEING A TSTORM THIS EVENING
WITH MOST OF THE UPPER LEVEL SUPPORT REMAINING EAST. BETWEEN 8Z
AND 13Z THE SECOND SHORTWAVE WILL MOVE NORTH BRINGING HEAVIER RAIN
AND GREATER CHANCES FOR THUNDER. VFR CONDITIONS ARE EXPECTE TO
DETERIORATE WITH THE NEXT SHORTWAVE AND IN HEAVIER SHOWERS.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$

UPDATE...WISE
SHORT TERM...CONNELLY
LONG TERM...DORN
AVIATION...WISE



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